Purpose :
SMILE has been proved to offer many advantages compared with traditional refractive surgeries. The study aims to compare the expression of different cytokines associated with corneal wound healing and inflammation caused by FS-LASIK and SMILE procedure.

Methods :
16 eyes of 16 rabbits for each group underwent SMILE and FS-LASIK procedure separately. All eyes were treated for the same refractive correction of −6.00 DS/−1.00 DC. Eight eyes served as control. All rabbits were euthanized after 24 hours, 1 week, 4 weeks and 3 months postoperatively, respectively. The levels of IL-1, IL-6 and IL-8 in Aqueous humors were detected by ELISA. Corneal tissues were evaluated with TUNEL assay and immunocytochemistry for Ki-67. The expression of bFGF, TGF-β, EGF, IL-1 and TNF-α were determined by RT-qPCR and Western Blotting. Statistical analyses were performed using Independent samples t-test (P < 0.05).

Results :
There were significantly fewer TUNEL+ keratocytes around the interface (p=0.006), however more TUNEL+ epithelial cells (p=0.023) were detected after SMILE at 24h compared with the FS-LASIK procedure. In addition, fewer Ki67+ cells in the SMILE group than those in the FS-LASIK group were found only at 1 week (p=0.034). The mRNA level of IL-1β was significantly higher in FS-LASIK group at 24h, 1, 4 weeks(p=0.023, 0.001, 0.005), while the TNF-α level was only higher in FS-LASIK group at 24 h(p=0.006) than that in SMILE group. Western blot showed consistent results. However, the level of TGF-β increased significantly at 1 week and 4 weeks, and returned to control level at 3 month in both groups, and was significantly higher after SMILE at 24h and 1 week compared to the FS-LASIK (p=0.018, 0.011). The level of bFGF, EGF, EGFR in both groups also increased significantly at 24 hours compared to control. The IL-1, IL-6 and IL-8 level in aqueous humors were significantly higher in FS-LASIK group at 1 week postoperatively (p=0.003, 0.018, 0.025).

Conclusions :
SMILE procedure induces less stromal and more epithelial apoptosis, less proliferation, less and shorter inflammatory responses compare to FS-LASIK procedure. Corneal wound healing still exist at 1 month postoperatively, which suggests that it is necessary for patients to take routine examination and proper medication at 1 month after procedures.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.